This invention relates generally to airflow systems, and more particularly, to a damper for regulating and diffusing the airflow through an air inlet to various areas, such as clean room air filter systems.
Many types of rooms, such as clean rooms commonly used in many industries, such as the electronic, medical and pharmaceutical industries, use dampers to control airflow to filter systems to reduce the number of particles in the air to specified limitations. In the most common approach, a layer of flat filters is suspended from a room ceiling or a sidewall, with the filters extending over the entire area of the ceiling or sidewall. Air is conducted from a blower through ductwork or a pressurized plenum and then through the filters into an open space in the clean room. The air is returned back to the blower or plenum by way of outlets in the room. The air in the clean room is at an elevated pressure to keep tainted or unfiltered air out. Preferably, airflow into the clean room is controlled by valves or dampers positioned between the blowers or pressurized plenum and the filter elements. Accurate control of the airflow is necessary to maintain desired flow rates and a pressurized clean room. Many attempts have been made to provide for improved control valves or dampers for regulating the airflow into clean rooms.
In U.S. Pat. No. 4,666,477 to Lough, there is described a clean room adjustable damper in which a fixed plate having a plurality of apertures has a movable foam plate having a further plurality of apertures mounted over the fixed plate. Relative movement between the plates moves the apertures into and out of alignment to control the flow of air to the filter element. Movement is obtained by rotating a cam that operates against a cam surface to laterally shift the movable foam plate with respect to the fixed plate.
Other systems are known that also laterally move adjacent plates having aligned openings therein to control the flow of air through clean room filter systems.
However, it is still desirable to provide an improved damper to more accurately and efficiently regulate and diffuse the flow of air from an air inlet into clean rooms and the like.
The present invention provides an improved damper for clean room filter systems that may be used in a ceiling or sidewall, and which is more efficient, better performing and easier to use. The present invention provides dampers that include a plurality of spaced apart plates that more positively regulate and diffuse airflow, and which allow for virtually complete shut off of airflow. The plurality of spaced-apart plates are supported from a filter lid panel, or other supporting surface, so as to be easily axially translatable from open to closed positions. Each plate member is reciprocally mounted on a support rod or control element, and includes a plurality of non-aligned apertures.
The dampers of the present invention can be utilized with any type of pressurized system, such as ducted, fan powered, or pressure plenum-type systems. All variations may be interchanged or mixed within a filter system. When used with ducted filter modules having hoods or lid panels, the dampers of the present invention are held or supported by the lid panels. Supply air duct work for the ducted filter module variation is attached directly to the upper side of the lid panel of each module, thus making the duct connection independent of the filter element in the module. Each ducted filter module lid panel includes a damper of the present invention at the supply duct connection to diffuse and vary the volume of supply air for balancing and fine-tuning, or to completely shut off the flow of air. The damper includes separate elements operating axially to the air inlet only, for more accurately and positively regulating and diffusing airflow.
It is, therefore, a general object of the present invention to provide an improved damper for airflow systems. It is a particular object of the present invention to provide an improved damper for clean room air filter systems comprised of individual filter modules. It is another particular object of the present invention to provide an improved damper for clean room air filter systems comprised of separate plates having a plurality of non-aligned apertures therein which move axially to the air inlet of the filter modules. It is yet another particular object of the present invention to provide an improved damper for clean room air filter systems that offers virtually complete shut off of airflow to filter modules. It is still a further particular object of the present invention to provide an improved damper for clean room air filter systems that may be activated from the clean room side of the filter system.
These and other objects of the present invention are achieved by providing a damper for air flow systems, which damper has a plurality of axially movable plates supported from a filter module lid, ceiling or other support surface having an air inlet therein. Each axially movable plate has a plurality of apertures therein, which apertures are not aligned, for regulating and diffusing the flow of air blown from an air supply system therethrough. Gaskets cooperate with the movable plates to seal the same, and the damper includes a central rotating drive member to operate the plurality of movable plates between open and closed positions.